jelenko
Gold $$ Contributor
And, there is somewhat hard carbon. In my experience good solvents like C4 will remove them while others struggle or not at all.Ahhhhhhhhh...another cleaning thread.
Removing hard carbon, like the baked-in volcanic glass kind of carbon, requires mechanical action, period. There is no single safe cleaning agent or solvent that can clean everything without some kind of mechanical action such as a bronze brush and/or occasional treatment with abrasive cleaners. Anyone tells you different, you probably don't want to be listening to them.
The main reason for using a carbon cleaner such as C4 first is to remove most of the carbon deposits so that the subsequent copper-remover can work with maximum efficiency. If there is a layer of copper underneath the carbon deposits, the copper cleaner may not be working optimally until sufficient patches have been put through the bore to get most of the carbon out. Boretech Eliminator is formulated to remove both carbon and copper, whereas C4 is primarily a carbon remover. I use C4 carbon remover first, followed by Cu+2 copper remover, combined with bronze brush treatment at each step. This approach works pretty well for me, but that is solely my opinion.
A significant amount of loose carbon fouling can actually be removed by simply running some patches wetted with nothing more than ordinary tap water, or some benign organic solvent such as acetone or methanol. If you don't believe that, try it. Is tap water or acetone/methanol as good as C4? I don't think so, or I wouldn't spend the money for C4. Nonetheless, it's not all that difficult to remove a significant amount of loose carbon fouling. Hard carbon is a different story as I mentioned above. I mention this because a long time ago, I used to use only the Cu+2 copper remover for both carbon and copper. That approach in combination with bronze brush treatment worked, but I think using the C4 first does a little better job of getting most of the carbon out. It certainly seems to come out a little easier and more completely using C4 followed by Cu+2.
The bottom line is that there are numerous commercial barrel-cleaning agents available. Everyone has their favorites. Most of them will work, but perhaps with varying degrees of efficacy. IMO, the main difference between them is not whether they will work at all, but one of the effort involved. In other words, how many patches does a particular cleaning agent require and how much additional mechanical effort does it take to really get the bore clean? So the specific brand of cleaning agent(s) someone chooses and the order in which they choose to use them is really a personal choice, nothing more. Most will work if sufficient effort and some kind of mechanical action are applied.
This brings up a question: No matter how good the chemical solvent is, will brushing with a bronze brush remove more carbon? I think it will. Next time I clean a barrel I'm going to experiment and assess the difference by observing the bore after cleaning as well as possible with just patches and solvent; then looking again after brushing.